1 Department of Respiratory Medicine, Royal Brompton Hospital, Guy's and St. Thomas' NHS Foundation Trust, London, UK. s.anand@imperial.ac.uk.
2 MRC Centre of Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK. s.anand@imperial.ac.uk.
3 Department of Respiratory Medicine, Royal Brompton Hospital, Guy's and St. Thomas' NHS Foundation Trust, London, UK.
4 Faculty of Medicine, Department of Infectious Disease, Imperial College London, London, UK.
5 MRC Centre for Molecular Bacteriology and Infection, London, UK.
6 Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.